Physical vapor deposition is a process used widely in film coating applications. A substrate is positioned in an apparatus having a component made of the material to be deposited onto the substrate disposed therein. The component is usually coupled to an electrode in some way to enable establishing an electric field around the target component. The electric field is used to ionize a gas in the vicinity of the target component and accelerate the ions toward the target, and magnets are used to confine electrons to an area near the target so they can further ionize gas atoms before they flow to an electrode or to the chamber wall. Ion collisions with the target dislodge material from the target, and the material falls onto the substrate, forming a film coating thereon.
In some manufacturing processes, multiple films are deposited on one substrate. In some cases, more than one film may be deposited in a single chamber, but in most cases, multiple chambers are used in sequential deposition processes. When depositing thin films, thickness uniformity across the film is desired, and many measures are used to adjust deposition uniformity across a substrate. In multi-chamber processes, defects in uniformity from chamber to chamber must also be managed. In some processes, chambers that are physically connected to facilitate transport of substrates between them can also give rise to operational interactions between the chambers that can adversely affect deposition rate and uniformity. Thus, there is a continuing need for methods of operating connected process chambers in ways that promote uniform deposition.